WATER RESOURCES OF THE ECONFINA CREEK BASIN AREA IN...

STATE OF FLORIDA

STATE BOARD OF CONSERVATION

DIVISION OF GEOLOGY

FLORIDA GEOLOGICAL SURVEY

Robert O. Vernon, Director

REPORT OF INVESTIGATIONS NO. 41

WATER RESOURCES

OF THE

ECONFINA CREEK BASIN AREA

IN

NORTHWESTERN FLORIDABy

R. H. Musgrove, J. B. Foster, and L. G. Toler

Prepared by the

UNITED STATES GEOLOGICAL SURVEY

in cooperation with the

FLORIDA GEOLOGICAL SURVEY

TALLAHASSEE

1965

FLORIDA STATE BOARD

OF

CONSERVATION

HAYDON BURNS

Governor

TOM ADAMS EARL FAIRCLOTH

Secretary of State Attorney General

BROWARD WILLIAMS FRED O. DICKINSON, JR.

Treasurer Comptroller

FLOYD T. CHRISTIAN DOYLE CONNER

Superintendent of Public Instruction Commissioner of Agriculture

W. RANDOLPH HODGES

Director

LETTER OF TRANSMITTAL

01D WE 11'

9 7 orida jeological Qlurvey

TALLAHASSEE

July 20, 1965

Honorable Haydon Burns, ChairmanFlorida State Board of ConservationTallahassee, Florida

Dear Governor Burns:

The Florida Geological Survey will publish, as Report of Investi-gations No. 41, a comprehensive report on the water resources of theEconfina Creek Basin area in northwestern Florida. This report wasprepared by the members of the U. S. Geological Survey in coopera-tion with the Florida Geological Survey, as a part of its waterresources study program.

The Econfina Creek is one of the largest discharging streams ofthe State, and its potential for meeting water resources needs is great.The publication of the total resources study, to be accomplished ina series of papers, will contribute toward the stabilization of theeconomic development of the Panhandle area, and will provide abasis upon which a large water-using economy can be based.

Respectfully yours,Robert O. Vernon,Director and State Geologist

Completed manuscript received

April 30, 1965

Published for the Florida Geological Survey

By The St. Petersburg Printing Co., Inc.

St. Petersburg, Florida

1965

PREFACE

In the planning and preparation of this report we have tried topresent the essential information that would provide a brief, concisedescription of the water resources of the Econfina Creek basin area.The report was designed to supply answers to general questions ofthe many people interested in the water resources of the basin. Otherreports on particular aspects of the water resources of the basin willpresent more detailed information about a phase of the hydrology orgeology of the basin. This report is intended to furnish the back-ground from which the reader may refer to the phase reports for moredefinitive treatments of a particular subject.

Special phases of the water resources of the basin will be featuredin reports on: Deer Point Lake; The Deadening area of southeasternWashington County; geology and aquifers of Bay County; and aquantitative study of ground water in the Panama City area. In addi-tion, the basic data available through the period of investigationwill be published in the information circular series of the FloridaSGeological Survey.

This report was prepared by the Water Resources Division of theU. S. Geological Survey in cooperation with the Florida GeologicalSurvey. The investigation was under the general supervision of RobertO. Vernon, Director, Division of Geology, State Board of Conserva-tion; A. O. Patterson, district engineer, Surface Water Branch; C. S.Conover, district engineer, Ground Water Branch; and K. A. MacKichan, district engineer, Quality of Water Branch, of the U. S.Geological Survey.

A number of individuals and organizations have been most gener-ous in supplying information, equipment, and time in the process ofcollecting data for this report. The courtesies extended by the follow-ing persons are most appreciated: W. C. Cooper of W. C. CooperPlumbing and Heating Co.; H. L. Berkstresser and W. H. Gallowayof the Water and Sewage Department of Panama City; G. Layman,construction engineer for Gulf Power Co.; W. H. Toske and M. G.Southall of the U. S. Navy Mine Defense Laboratory; R. B. Nixonand J. L. Gore of the Tyndall Air Force Base water department; J. M.Lowery and T. M. Jones of the International Paper Co.; A. G. Symonsand R. H. Brown of the Layne-Central Co.; W. Brown of the BrownWell and Pump Co.; and J. W. Spiva of Modern Water Inc.

Data on the chloride content in water from Deer Point Lakeduring the period of freshening were furnished by the Florida StateBoard of Health.

V

PREFACE

We would like to express special appreciation to Judge Ira A.Hutchison who through his interest in water resources and in par-ticular the geology of this area has been most helpful. Claude Hickshas volunteered invaluable assistance in the collection of water-levelinformation in the Deadening lakes area.

We would like to thank the numerous citizens in the basin whogave us access to their wells and who furnished us with informationon their water supplies.

vi

CONTENTS

Page

Preface .............. ---... ---...---- --......--.. .-----..-..-.---- v

Abstract ...-....................... .-------------------------- --- ............-- ........... 1

[ntroduction ---...........---..-.........- ....... . .... ---. ---.. .........---- 2

The hydrologic environment ---..--............-..-..------------------- 4

General statement ..........................---------- ----------- 4

Physical make-up of the basin ...........-............------ ---..-- ..----... 4

Water movement .-.....---....--------------------------- 7

Water availability .........--....................- ----- ---------------- 8

Rainfall ...................... ........ ..... ..---- --------- --------- ------- 8

Water quality characteristics .--..-...-....-........-------- .--------- 9

Contamination by saline water .-......-...............----.........------- 11

Streamflow ..-.......-...--------..........----- ------------------ 15

Storage . -..~.......---.......-.....-- .--.-------- ---------------- 18

Lakes ..--............ .. -------.---. --------- -------- 18

Aquifers ......-...........--..-- -------------- -------- 19

Aquifer characteristics ................---------------------------- 20

Hydraulics of aquifers ......-........-- .....--.--- ---- ------------ 22

Aquifer tests ....-...................-- ..-------------------- 24

Water use ......................---------- ---------------------------- 27

Water high lights of the basin .--.............-... --------------------- 29

Decline of water levels in the Panama City area ...---...---...--...--..-.......----.. 29

General statement .........-- ........---------------------- 29

History of ground-water development ..--------................. ............. 31

vii

Page

The Deadening lakes ...................................... . ..............---- 35

Geologic and hydrologic setting ..--......--..-..........---------------- 37

Water levels ...--............---.......--------------------- 37

Flow of Econfina Creek .......-.................------- ------------- 40

Springs ---..........-...--..--..-...-------------- ----------- 41

Deer Point Lake .........--.....---- ---------------------- 45

Summary -..-----.---- -------------------------.----- 45

References .......-..---........----------------------------- 51

viii

ILLUSTRATIONS

Figure Page

1 Map of Econfina Creek basin area ........--......................---............. 3

2 Map of Econfina Creek basin showing physiographic divisions andsurface runoff --................. ....-- .-..-- ..--.......--.......-....--.................. Facing p. 4

3 Geohydrologic sections of Econfina Creek basin area --...-..-.......----...-...--. 6

4 Bar graphs of maximum, minimum, and average monthly rainfall, andannual rainfall, at Panama City from 1935 to 1963 ....-........-.....-....---- ..---- 9

5 Map of Econfina Creek basin area showing location of data-collectionpoints referenced in report -....--.......-...-..----.....--.....---------------...............-.... 12

6 Scatter diagram showing relation of chloride to total mineral contentof water from the Floridan aquifer in the Econfina Creek basin area .... 13

7 Block diagram of Econfina Creek basin showing areal distribution ofmineral content and chloride concentration in water from selected wellsin the Floridan aquifer -....--...--.............- . .......- ................... -......... . ......-- 14

8 Graphs of chloride concentration in water from selected wells in theFloridan aquifer .............------..--.......-....-........--......-- .. ....------------.---- 15

9 Flow chart of streams in the Econfina Creek basin -..-....--...---........-....-- ... -- 17

10 Graphs of water level in the water-table aquifer and rainfall nearBennett for part of 1962 and 1963 ..----.......----......................--.......-- .-- . 19

11 Graph of streamflow of Econfina Creek near Compass Lake for theperiod April 1 to May 7, 1963 ......-..-...-........--------..-- ..-- .------. -----. 20

12 Sketch showing similarity of an artesian pressure system and waterpressure developed by an elevated tank .--..........---.................------ ..------ 21

13 Map showing the piezometric surface of the Floridan aquifer in theEconfina Creek basin area, October 1962 ...----.........-..---...--...-...--- --.-- 23

14 Graphs showing theoretical drawdowns in the vicinity of wells beingpumped at a constant rate for selected periods .....-...-.....-...........-...-- ...... 26

15 Theoretical drawdowns along a line of 10 wells after 100 days ofpumping at a rate of 200 gallons per minute at each well -..--.....-..--.... 27

16 Graphs of water use and population in the Panama City area -...-....-.... 30

17 Map of the Panama City area showing the location of water wells foreach water system and the area supplied by these systems -..--..-..........--.. 31

18 Map showing the approximate piezometric surface of the Floridanaquifer in the Panama City area in 1908 ---.........---..-.--... -~.. ------. 32

ix

Figure Page

19 Graph of water levels in observation well 008-537-332 near the centerof the International Paper Company well field for the period 1951to 1963 .-..-..-.........................- .................-........-..............................----........... . 33

20 Map showing the piezometric surface of the Floridan aquifer in thePanama City area in April 1947 ....-......--.......-...................--...-..................... -35

21 Map of White Oak Creek basin in southeastern Washington Countyshowing The Deadening area ..-..-.........-................. .... ...-------........................ 36

22 Geohydrologic sections through the White Oak Creek basin, south-eastern W ashington County .............................-.............. .......-- ......----- -....... 38

23 Graphs of water levels and rainfall in the vicinity of the Deadeninglakes .....----------------------.. ....... .... .............. ....................... ................. ........ 39

24 Flow chart of Econfina Creek during the low-water period of May 1963showing the effect on streamflow if 30 mgd were diverted at the proposeddam site ..--.......-..-- ...-...-..... ------------- - --------------------.................................. 42

25 Flow chart of Econfina Creek showing spring flow ......-............................... 43

26 Graphs of streamflow, spring flow, and specific conductance for EconfinaCreek near Bennett for 1963 ..----.......................... ................- ...................... 44

27 Graph showing the relation of chloride in water in Deer Point Lake tofresh water inflow --...-----.. .... ...........-----------------.......................... 46

28 Graphs showing the rise of water levels and change in chloride contentof ground water after construction of Deer Point Dam ...............--.....-..-- .. 47

TABLES

Table Page

1 Drainage areas, average flows, and low flows of subbasins within theEconfina Creek basin ------ -----............-------------------.................................. 16

2 Record of water supply systems in the Econfina Creek Basin area .......... 28

x

WATER RESOURCES

OF THE

ECONFINA CREEK BASIN AREAIN

NORTHWESTERN FLORIDA

By

R. H. Musgrove, J. B. Foster, and L. G. Toler

ABSTRACT

The Econfina Creek basin area of about 1,000 square miles islocated in northwestern Florida. Water use in the basin in 1963averaged about 25.2 mgd (million gallons per day). The major usesof water were for the manufacture of paper products, public anddomestic supplies, and recreation. Of the 25.2 mgd, 22.7 were pumpedfrom the artesian Floridan aquifer, mostly in the Panama City area.In February 1964 use of lake water was started at the rate of about30 mgd and ground-water withdrawal was reduced to about 11 mgd.Since February 1964 the total use of water in the area has been about41 mgd.

The basin receives most of its water from rainfall which averages58.0 inches per year. Highly porous, unconsolidated sands form thewater-table aquifer and absorb much of the rainfall. Seepage fromthis aquifer is to the streams and to the underlying artesian aquifers.The productive artesian Floridan aquifer underlies the entire basinand is the aquifer from which the most water is pumped. A secondaryartesian aquifer is present in the southern part of the basin and isintermediate in depth to the water-table and Floridan aquifers. Move-ment of water through these aquifers is generally southwestward.

By 1963, water levels in the Floridan aquifer near Panama Cityhad been lowered 200 feet by pumping since the first deep well wasdrilled in 1908. The large drawdowns resulted from heavy pumping ofclosely spaced wells in this aquifer which has a low transmissibility(1,300 to 31,000 gallons per day per foot). In January 1964, pump-age from a field of 21 wells was stopped and water levels in this fieldrecovered 163 feet within 51 days.

Water from the water-table aquifer generally had a mineral con-tent from 10 to 50 ppm (parts per million) and that from the sec-

1

2 FLORIDA GEOLOGICAL SURVEY

ondary artesian aquifer from 80 to 150 ppm. Water from the Floridanaquifer increased in mineral content from 70 ppm in the northernpart to about 700 ppm in the southern part of the basin. Mineralcontent of water from streams and lakes, exclusive of those receivingartesian spring flow, was from 6 to 25 ppm. Water from springs hada mineral content from 50 to 68 ppm and was similar to water fromthe Floridan aquifer in the upper part of the basin.

Streamflow into the coastal bays is at an average of about 960mgd. Flow to North Bay is about 680 mgd, of which about 650 mgdflows through Deer Point Lake. East Bay receives about 210 mgd,and West Bay about 70 mgd. Runoff from the lower half of the drain-age of Econfina Creek is 90 inches per year. This is about three timesthe runoff from the upper half of the basin and is a result of artesianspring flow.

There are about 80 named lakes in the basin, some of which havea wide range in stage. A plan has been proposed to divert water fromEconfina Creek to a group of these lakes in southeastern WashingtonCounty to stabilize their levels. At the proposed point of diversion,Econfina Creek has a minimum flow of 30 mgd, which would supplyabout 0.5 of a foot of water per month on the proposed lake area.

INTRODUCTION

This report describes and evaluates the water resources of theEconfina Creek basin area located in northwestern Florida. The areaencompasses about 1,000 square miles and includes most of BayCounty and parts of Calhoun, Gulf, Jackson, and Washington coun-ties, as shown in figure 1. As considered in this report, the EconfinaCreek basin area includes all basins that drain into the bay systemwithin Bay County.

Over 90 percent of the 70,000 people in the basin are located nearthe coast and are centered in the Panama City area. In 1963, wateruse in the basin was at the rate of 25.2 mgd. The three largest waterusers were the International Paper Company, Panama City, andTyndall Air Force Base.

Ground-water levels were known to be below sea level in wellfields supplying the major users. Information was needed to determinethe extent of the low water levels and their effect on the water re-sources of the area.

More than 80 fresh-water lakes are situated in the higher partsof the area, mostly in southeastern Washington County. Includedis a group of lakes locally known as The Deadening. Considerable

REPORT OF INVESTIGATIONS No. 41 3

486Od 5e 50 45 4d 3 3 2 2'd 1 aSid

WIDr,

2 0 1 2; 4 25 Ml WNW

5.IV N -1 - 5

N52 0 d - o2 5

Figure 1. Map of Econfina Creek basin area.

interest has been expressed concerning the development of The Dead-ening lakes into a water-oriented recreational area. Widely fluctu-ating lake levels rendered this recreation plan infeasible withoutlake controls. The Washington County Development Authority hasa plan to stabilize these lakes by water diverted from Econfina Creek.Data were collected during the investigation to evaluate this plan.

No formal reports on the water resources of the area were avail-able before this investigation. Some data were available on ground-water levels, streamflow, and the chemistry of ground water. Thisreport is based on a 2-year investigation which began in January1962. The investigation was designed to provide a basis for an evalu-ation of the water resources of the Econfina Creek basin.


THE HYDROLOGIC ENVIRONMENT

GENERAL STATEMENT

Water in the natural state continually moves due to many forcesacting upon it. Gravity acts on water in streams and undergroundto keep it moving downward toward the level of the ocean. The sunand wind evaporate water from open water bodies and plants trans-pire water to the atmosphere. Gravity again moves the water earth-ward when the atmospheric moisture meets conditions favorable forrain. This never ending movement of water is known as the hydro-logic cycle.

The water resources of any area depend upon this hydrologiccycle. When the rate of water movement out of an area exceeds therate of water movement into the area, water shortages will develop.Water shortages may also develop if the quality of water is signifi-cantly altered within its natural environment to make it unfit for itsintended use. Variations in the rate of movement in any phase of thehydrologic cycle, such as rainfall, may also affect an area by result-ing in floods and droughts. Proper development of the water resourcesof an area requires a thorough knowledge of water movement andthe factors controlling it. This knowledge will enable the best pre-diction of where to obtain water and what provisions are requiredto control water movement.

In general, the system through which water moves in the Econ-fina Creek basin is similar to most river basins in Florida. Like mostother basins, (1) rainfall is the source of all the water even thoughsome falls outside the basin and moves into the basin underground;(2) the surface materials are highly porous, unconsolidated sands;(3) the basin is underlain by the artesian Floridan aquifer; and(4) water leaves the basin by streamflow, evaporation, transpira-tion, underground flow to the ocean and other basins, and by con-sumptive use.

PHYSICAL MAKEUP OF THE BASIN

Four physiographic divisions within the basin affect the surfacedrainage and the water storage. These are the sand hills, sinks andlakes, the flat-woods forest, and the coastal beach sand dunes andwave-cut bluffs, shown in figure 2. The physiographic divisions havedeveloped on a series of stair-step marine terraces which were carvedinto the surface sands during the ice age by the successive levels of

86"00' 55 50' 45 40 35 30 25' 20 15' 83*10

ECONFINA CREEK BASIN AREA E

30035ý 30'333 GREENHEA i

II0

TAIN

1 0 1 2 3 4 5 Miles

Esr !2d

IO CITEXPLANATION

PHYSIOGRAPHIC DIVISIONS 5

al Sand hills A,

C 0 ,: Sinks and lakes aIiMaia Flat- woods forest

S30W- Beach dunes and wave-cut bluffs

37 Numbers represent average annualrunoff in inches from areas out- Tr-EWAylined by dashed lines,

8o0 55' 50 45' 40' 35' 30' 25' 20' 15' 85•10'

Figure 2. Map of Econfina Creek basin showing physiographic divisions andsurface runoff.


the ocean. Low swampy areas occur throughout each of these divi-sions but are more prevalent in the flat-woods forest.

The sand hills in the northern part of the basin are erosionalremnants of the higher marine terraces which were between 100 feetand 270 feet above the present sea level.

The sinks and lakes occur in the section of the basin west ofEconfina Creek where they have developed within the sand hills. Thisarea is typified by irregular sand hills and numerous sink holes andsink-hole lakes. The sink holes range in diameter from a few feet tobroad flat areas such as those in The Deadening lakes area (see p. 73).This physiographic division was developed by the solution of theunderlying limestone and the subsequent collapse of the overlyingmaterial into the solution chambers. Most of the lakes have no sur-face outlets.

The flat-woods forest is the largest physiographic division of thebasin. It is slightly rolling to flat land lying on the terraces below anelevation of 70 feet. Most of this division is covered with pines exceptfor a few small areas cleared for agriculture. The flat-woods forest iswell drained except for some low areas around the bays on the 0 to10 and 10 to 25 foot terraces. During rainy weather these low areasof the flat woods become quite wet. A few small perennial swampsoccur at various locations throughout the flat-woods forest. The larg-est is Bearthick Swamp southeast of Youngstown which covers anarea of about 2,000 acres (fig. 2).

The fourth physiographic division occurs adjacent to the gulfcoast and is characterized by beach dune deposits and wave-cut bluffs.The beach dune deposits are the youngest sediments in the basin andare the most rapidly changing physiographic feature.

The surface materials in the basin, on which the physiographicfeatures have developed, are generally very porous, permeable sands.The sands form the water-table aquifer which is thicker in the sandhills (80 to 100 feet) than in the lower elevations of the flat-woodsforest (10 to 30 feet) and thickens again along the coast (65 to 140feet). The sands are missing only in stream channels and in someparts of the broad depressions of the sinks and lakes division.

The sands of the water-table aquifer cover a relatively imperme-able layer of sandy clay and clayey shell material which forms anaquiclude (a formation that confines water to aquifers above andbelow it) between the water-table aquifer and the artesian aquifersbelow it, as shown in figure 3. This aquiclude is present throughoutthe basin except where it has been breached by a collapse into solu-tion chambers or by erosion along Econfina Creek.

240 - I -240

10 -0 160Sso

So level 0 - - - - - - 0 Seatle

F I D AN AQU IFER EXPLANATIONL

T ! I "T -0 So1 i w80- - .4 ... r. 1 . r. - .60

240 Sond 240

SShells -320400 Clay -400

, ;, .. Limestone j" . ,--49 0

so .-I A AE : : : jo

• , • • S _ • I T ., e.,

-- - ---AQUICLUDE g. - " ." . .. " E !-,- ',.. -16A -- u u .. " - - -- AQUICLUDE -UICL- 1 LUDE

0- 1 1 1 l 320

400 -400

FLORIDAN AQUIFER

.640 1 1 - i .640

0 1 2 3 4i 5 10 miles

Figure 3. Geohydrologic sections of Econfina Creek basin area.

REPORT OF INVESTIGATIONS NO. 41 7

In the bay area and along the gulf coast in the basin, two artesianaquifers are associated with the aquiclude. Here the aquiclude isthicker than it is to the north and is overlain and in part underlainby some shell-hash beds which contain water. The sandy clay materialwhich forms the base of the water-table aquifer is sufficiently imperm-eable to confine water in the shell-hash beds under artesian pressure.Water producing zones in the shell-hash beds above the aquicludeare termed the secondary artesian aquifer. The water producing zonesin the shell-hash beds below the aquiclude are considered part of theFloridan aquifer.

The Floridan aquifer underlies the entire basin below the aqui-clude. It is composed of limestone formations that are as much as1,200 feet thick. However, the usable part of the aquifer, the partproducing potable water, is the upper 500 to 700 feet.

WATER MOVEMENT

Rain, falling on the basin, is readily absorbed by the porous sur-face sands. The portion that runs off directly to the streams dependson the amount and intensity of the rainfall. The rain water and thesurface water are relatively pure but contain some salts carried inthe evaporate from the ocean and some gases dissolved from the at-mosphere. The surface water becomes colored after contact withdecayed organic matter but the mineral content changes very little.

The water absorbed by the sands seeps downward to the watertable, the level below which the sand is saturated. The sands are notvery soluble in the rain water and consequently the mineral concen-tration in water from the water-table aquifer is low.

Some of the water then moves from the water-table aquifer intothe streams and maintains flow during periods of no rainfall. In thenorthern part of the basin where the sand and clay are breached bysinkholes, some of the runoff and seepage from the sands is tempo-rarily ponded in lakes and then moves into the Floridan aquifer. Inother areas the water from the sands may seep slowly into the lime-stone through the clay layer.

The amount of water moving from the water-table aquifer to theFloridan aquifer diminishes toward the southwest because the aqui-clude is thicker. Water that moves downward into the limestone ofthe Floridan aquifer then moves in the down gradient direction shownby the piezometric map (see p. 23). The gases acquired from the at-mosphere and from the soil zone form a weak acid solution which dis-solves the limestone and thereby causes an increase in the mineralI


content of the water. The mineral content of the water increases inthe down gradient direction as more limestone is dissolved.

In areas along Econfina Creek where the artesian pressure surfaceis above the land surface and the sand and clay are missing, springshave developed. Most of the flow of Econfina Creek is derived fromthese springs.

In the southern half of the basin, water may percolate downwardfrom the water-table aquifer into the secondary artesian aquifer. Thesandy clay material at the base of the water-table aquifer and at thetop of the secondary artesian aquifer acts as a semi-confining layerwhich maintains the water in this aquifer under artesian conditions.

The secondary artesian aquifer is composed of shell-hash withinterlayered sand and limestone lenses. Water that moves into thisaquifer from the water-table aquifer is slightly acid. This waterdissolves the limestone and shell giving the water a calcium bicarb-onate character.

The water withdrawn from wells in the Floridan aquifer in thePanama City area entered the aquifer through the sinks in the north-ern part of the basin and in areas farther north where the limestoneformations are at ground surface. By the time the water reachesPanama City the mineral concentration is five to six times that ofwater in the northern part of the basin. Part of the increase is causedby solution of the limestone and part is caused by mixing with olderwater in the rocks. The pressure gradient shows that the water is beingflushed into the ocean at some point where the rocks are exposed toor hydraulically connected to the ocean bottom.

WATER AVAILABILITY

The amount of water moving through each part of the hydrologicsystem must be known to properly evaluate a water resource. Aknowledge of the environment is necessary to determine the chemicaland physical properties of the water and to predict any changes inthese properties that may result from withdrawal of water from thesystem. Some of the parameters that affect the amount and qualityof water available are rainfall, streamflow, water levels, rock com-position, and the ability of aquifers to store and transmit water.These hydrologic features can be measured either by direct or in-direct methods.

RAINFALL

The Econfina Creek basin receives an average rainfall of 58 inchesper year, based on records collected at Panama City by the U. S.


Weather Bureau. During the past 29 years the annual rainfall atPanama City has varied from 37.6 inches to 85.0 inches. Graphsshowing variations in rainfall are given in figure 4. Short periods

25 100

W 2 0

-8 0

iAVERAGE 57.98

Z MAXIMUM

95 60 F,

10 40 -

ZLAG

AVER GS5 20

0 0JIFMIAIMIJ IJIA SIOINID to o 0 o 0 oI q I It 9) (0 I I

Figure 4. Bar graphs of maximum, minimum, and average monthly rainfall,and annual rainfall, at Panama City from 1935 to 1963.

of low rainfall and short periods of high rainfall have little directeffect on the water resources; that is, the amount of water in storage.Extended periods of below-average rainfall, or droughts, cause reduc-tion in storage. The most severe drought of record ended in 1956with a 7-year deficiency in rainfall of 50.2 inches. Within this 7-yearperiod, 1953 was a single year of above-average rainfall but did notbring about a complete recovery of water lost from storage during

Sthe preceding years of low rainfall. The 6-year period from 1944 to1949 was the wettest of record. Records of water levels indicate thatstorage was near an all-time high during this wet period.

WATER QUALITY CHARACTERISTICS

The water in the lakes and streams of the area has about thesame mineral concentration as rain water. Samples of rain watercontained as much as 13 ppm of dissolved mineral matter; the waterin the streams and lakes ranged from about 6 to 25 ppm. The mineralconcentration of the surface water differs little from rainwater becauseof the relative insolubility of the surface materials. During periodsof low flow, high mineral concentrations are normally expected instream water because a large part of the flow is seepage from the


water-table aquifer. No difference in the chemistry of surface waterin the basin was noted between high and low flow except for the colorand pH. High color immediately following a rain is attributed to theflushing of the decayed organic material from the swampy, poorlydrained areas adjacent to the streams. This same colored water tendsto be acid due to the solution of carbon dioxide released from thedecaying plants. The pH of the streams is lower (more acid) duringhigh flow when the flushing of the swampy areas occurs. The pHnormally ranges from 6.0 to 7.0 units but falls below 6.0 duringthese times.

Two areas of exception to the normal low mineral concentrationin stream water occur in the Econfina Creek basin. One of the areasis along Econfina Creek downstream from a point about due east ofPorter Lake, where the creek receives flow from artesian springs.These springs emanate from limestones of the Floridan aquifer andthe chemistry and relative solubility of the rocks are reflected in themineral constituents found in the water. The mineral concentrationin water from the springs ranged from 50 to 68 ppm and all but about10 to 12 ppm were calcium and magnesium carbonate, the constituentsof limestone. The mineral content of the water in Econfina Creek,downstream from where spring water enters, is higher than that inother streams in the basin, and varies with the ratio of spring flowto surface runoff. Calculations, based on chemical analyses, (seep. 84), show that 70 to 75 percent of the base flow of Econfina Creekat the Bennett gaging station is from springs.

The other area of exception to normal low mineral concentrationsin stream water is near the mouth of the streams which empty intosalt-water bays. Salt water moves up the streams a distance that isdependent upon the elevation of the streambeds, the stage of thestreams, and tides. This encroachment of saline water occurs in themouths of all streams except those emptying into Deer Point Lake,which is a fresh water body.

That part of the rainwater that replenishes the aquifers continuesto move in the hydrologic cycle but at a slower rate than the watermoving as surface flow. This slow rate of movement allows a state ofchemical equilibrium to be approached and normally results in groundwater having a higher concentration of mineral constituents than doesthe surface water in an area. The highly insoluble nature of the sandswhich form the water-table aquifer in the Econfina Creek basinresults in low mineral concentration of water in this aquifer. Gen-erally, the concentration of total mineral constituents in water fromthis aquifer ranged from 10 ppm (about equal to that of rainwater)


,o about 50 ppm. In areas near the coast these sands are in contact

vith salt water. All water from the water-table aquifer which con-tained more than 50 ppm dissolved minerals was from wells locatedwithin a few hundred feet of salt-water bodies.

Water in the secondary artesian aquifer is slightly more mineral-ized than water in the water-table aquifer. In some areas near thecoast the water from this aquifer may be saline. Where there is nocontamination by saline water, the water generally contains from 80to 150 ppm dissolved minerals and is principally a calcium bicarbonatewater. Most of the water samples contained hydrogen sulfide and somesamples contained sulfate.

The mineral concentration of water from the Floridan aquifer ishigher than that from the secondary artesian or the water-tableaquifers. In the northern part of the basin the higher mineral contentis due entirely to higher concentrations of calcium and bicarbonateresulting from solution of the limestone. There are definite trends inmineral concentrations in water in the Floridan aquifer. These trendshave been mapped (Toler and Shampine, 1964) and generally showincreases in all constituents toward the southwest. An adaptation ofthe map of dissolved solids is shown on page 14 and indicates thetrend of all the constituents. Sulfate, sodium, and hydrogen sulfideshow little trend, but are found in significant quantities in thesouthern half of the basin. In this area, sulfate ranged from 0 to81 ppm, sodium from 2 to 164 ppm, and the odor of hydrogen sulfidewas detected in water from most wells.

CONTAMINATION BY SALINE WATER

The large bays in the southern half of the Econfina Creek basinprovide an access for salt water several miles inland. Along the shore-

line of these bays and along the Gulf, the salt water is in contact withthe sands which form the water-table aquifer. During droughts, whenthe water levels in the sands are low, salt water may enter the aquifer

and be pumped from shallow wells near the shore. Salt water is moredense than fresh water and it moves into the aquifer in the form ofa wedge below a lens of fresh water. Fresh water will generally sup-press the salt water about 40 feet below sea level for every foot ofelevation of fresh water above sea level. If the water level in the aquiferis lowered by pumping, the saline wedge adjusts to the new waterlevels and salt water may rise to contaminate a well. An interzone of

water of intermediate composition is normally present instead of asharp fresh-water salt-water interface.


Salt water may enter the secondary artesian aquifer from the baysor from the water-table aquifer, when the pressure surface of thesecondary artesian aquifer is below the water level of either source.Highly saline water from the secondary artesian aquifer was observedin samples from two wells. One well (007-535-334a), shown in figure 5

es a d 5d 4d d 3d sd 2a 2d I ad

30/ - - 45

4d

Figure 5. Map of Econffna basin area showing location of data-collection pointsreferenced in report.

is 76 feet deep and the water contained 1280 ppm chloride. The otherwell (008-545-224, fig. 5) is 101 feet deep and the water contained

W 2du

IS-LUMM A 32

well (008-545-224, fig. 5) is 101 feet deep and the water contained


1090 ppm chloride. Both of these are adjacent to saline surface-waterbodies. Wells penetrating the underlying Floridan aquifer, at andnear these locations, produce water low in chloride. The saline wateris presumed, therefore, to have leaked from the bays through thewater-table aquifer.

Apparently, the aquiclude overlying the Floridan aquifer (fig. 3)in the coastal and bay area is sufficiently impermeable to preventleakage of water from the overlying aquifers. The occurrence ofchloride in water in the Floridan aquifer does not appear to berelated to areas of high chloride in water in the overlying sedimentsor to the bays. Water levels in the Floridan aquifer have been loweredbelow water levels in both the water-table aquifer and the secondaryartesian aquifer, by pumping in the major well fields. Extended periodsof low water levels in the Floridan aquifer have not resulted in anincrease in the chloride concentration of water from this aquifer aswould be expected if the aquiclude were leaking.

The chloride content of the water increases southwestward, thegeneral direction of water movement. The fresh water apparentlymixes with saline water in the aquifer to account for the increase inchloride. Figure 6 shows the relation of the increase in total mineral

400

30

-J·-S 3 00 -------------- _---- _----_----_----_________

. Only those samples containing greaterthan 5 ppm chloride included **'

200

S00- _____ _____ _____ _____

0 100 200 300 400 500 600 700 800 900MINERAL CONTENT, IN PARTS PER MILLION

Figure 6. Scatter diagram showing relation of chloride to total mineral contentof water from the Floridan aquifer in the Econfina Creek basin area.

concentration of the water to the increase in chloride for all samplescontaining more than 5 ppm chloride.

Figure 7 is a block diagram of a section along the coast showingchloride concentrations and water producing intervals of wells pene-


I-C

20 Ch loide, in pm

S* Tap o hi Flaridan Aquifer---

„. 250- Oissolved solidi in parts per million s

'(Btfapt~id It Tolwe anid Shmples, 1904)

275

Well (number indicotes dissolved solids in ppm)

Figure 7. Block diagram of Econfina Creek basin showing areal distribution ofmineral content and chloride concentration in water from selected wells in the

Floridan aquif r.


trating the Floridan aquifer. The chloride concentration generallyincreases with depth into the aquifer. No chloride mineral is presentin the rock-forming materials and if water is not leaking from theoverlying rocks, then this saline water must be residual water thatremains in the rocks from a time when they were in contact with thesea. The geologic history (Foster, in preparation) indicates this mayhave happened many times. The residual water in the rocks would befrom sea water and chemically would probably differ little frompresent sea water.

Records of chloride content in water from four wells, from 1950 to1963, are given in figure 8. Although there is considerable variation

350 - 350

004-55\-333300- 4»7ff. d.ee -300

S010-43-42-- -.

2 -00 0 537-332 * 0'- 3o0

5 00.. 1e e

\ l 1'\ /\ /V .V.. .' 0-333-121 .S" - \ ft. d o" \ Pf 23

"'.'\ . l\ !. 0\' \ / \ I o o .1»«

I I .

30- 10

a 130 1951 1953Z 1I9 1934 155 1933 6 I23 2 203 19523 2160 2002 2062 0iri0

Figure 8. Graphs of chloride concentration in water from selected wells in theFloridan aquifer.

in the chloride concentration, there appears to be no long-term trendsdue to pumping.

STREAMFLOW

In using a stream, two quantitative aspects to be considered arechannel storage and the rate of flow. Channel storage is important inconsidering uses such as boating, fishing, and other recreational activi-ties. The rate of flow must be considered when determining the quan-tities of water that can be withdrawn from the stream at any time.Only the larger streams in the Econfina Creek basin have enough


channel storage during periods of low water to be used for boating.Most of the streams have sufficient flow to be a potential water sup-ply. During periods of minimum flows there is more than 10 times asmuch fresh water flowing into the bays than is being withdrawn fromall sources in the Panama City area.

Streamflow in the basin comes from several sources. During andimmediately following rains water flows directly into the streams asoverland flow. Between rains the streams receive only water that seepsfrom the shallow sands and from artesian spring flow from the lime-stone formations. Every stream receives seepage from the shallowsands.

Streamflow to the bays is at an average rate of about 960 mgdwhich amounts to 40 percent of the average rainfall. About 650 mgdflows through Deer Point Lake into North Bay from Econfina Creek,Bear Creek, Big Cedar Creek, and Bayou George Creek. Another 30mgd flows into North Bay below Deer Point Dam from smallerstreams. West Bay receives a flow of about 70 mgd from Burnt MillCreek, Big Crooked Creek and smaller tributaries. East Bay getsabout 210 mgd from Wetappo Creek, Sandy Creek, Calloway Creek,and smaller streams.

Figure 2 shows values of runoff from areas within the EconfinaCreek basin. It can be seen from this map that the physiographic fea-tures affect runoff. The low runoff in the southern half of the basinresults from the poor drainage of the flat-woods forest. Drainage in thesinks and lakes division is mostly internal and there is almost nosurface runoff. High base flow due to seepage from the porous sandscauses the high runoff in the sand hills division. The extremely highrunoff of 90 inches from the lower half of Econfina Creek is a resultof the artesian spring flow.

TABLE 1. Drainage areas, average flows, and low flowsof subbasins within the Econfina Creek basin.

Drainage area Average flow Low flowCreek basin sq. mi. mgd mgd

Econfina Creek --.....--..........................-.... 129 355 226Bear Creek .-------------.......... ........... ............... 128 226 52.Wetappo Creek ---...-.....-..................... ... -- 77 80 6Sandy Creek - ---------........ ................ .... 60 70 10Bayou George Creek ..---.......---...-- ... 51 26 3Burnt Mill Creek ---......... ................. 45 23 8Big Crooked Creek .....--........---..-....-----.. 22 17 6Big Cedar Creek -....... .. ....- ----.....-. . 62 12 4Calloway Creek .................... _.. __._.._. . 13 9 .6All others .....................-.......... - ........ - 142


Stream data are given in table 1. The values of streamflow, exceptthose for Econfina Creek, are estimated from short-term continuousdischarge records or from periodic discharge measurements. The lowflow of a stream without storage reservoirs limits its use. Much morewater can be taken from streams if storage reservoirs are availablefrom which to draw during periods of extreme low flows.

The flow chart in figure 9 shows the streamflow pattern of thebasin. The average flow of Econfina Creek is 355 mgd, by far the

largest of all the streams. This is a runoff of 58 inches per year and is

FLOW CHARTWidth of stream represents average

flow in million gallons- per day.

EI bFlow Scale fm e

L,° { A'SHINGTON .COUNTY. cBiN a T

COUNTY

i e 9Loke 1 0

FY 9. F hw George Creek

Figure 9. Flow chart of streams in the Econfina Creek basin.


about equal to the annual rainfall on the drainage area of 129 squaremiles. Streamflow records have been collected since 1936 at PorterBridge near Bennett at a point where the drainage area is 122 squaremiles.

The average flow of Econfina Creek from the upper half of thebasin is 90 mgd, only one-fourth of the flow from the entire basin.Upstream from Tenmile Creek (fig. 1) the flow during dry periods isseepage from the shallow sands. Downstream from Tenmile Creekartesian springs contribute most of the dry-weather flow. The mini-mum flow from the entire drainage area of Econfina Creek is about210 mgd, or seven times the minimum flow of about 30 mgd from theupper half of the drainage area.

Floods occur on Econfina Creek almost every year. The creek hasoverflowed its banks at least once each year in all but six of the last28 years. The longest period that it has stayed within its banks is the3-year period August 1950 to September 1953.

Bear Creek is the second largest creek in the basin and has anaverage flow of 226 mgd. It drains almost entirely from the sand hillsand flow is supported by seepage from these sands.

The average total surface flow into the bays was estimated as960 mgd. Econfina Creek and Bear Creek contribute 581 mgd of thisflow. The remainder of the average flow (379 mgd) comes from thesmaller streams in the basin. The larger streams are listed in table 1.

STORAGE

Rainfall, although it varies, supplies an adequate amount of waterto the basin. Water held in storage in lakes and aquifers eliminatesfrequent shortages which would result from the inconsistent rainfall.

LAKES

There are about 80 named lakes in the basin. Most of the lakesare in southeastern Washington County. Deer Point Lake (see p. 87),a fresh-water reservoir covering 4,700 acres in Bay County, is thelargest. Porter Lake in Washington County has a surface area of 930acres and is the largest natural lake.

The natural lakes have not been developed for water use to anygreat extent although they offer considerable potential as recreationalfacilities. Wide fluctuations in most lake levels, caused by seepagelosses to the ground and variations in rainfall, discourage their devel-opment. The Washington County Development Authority has pro-


posed a plan to divert water from Econfina Creek to a group of lakesknown as The Deadening (see p. 73) and thereby stabilize their levels.This plan, if executed, would add about 4,000 acres to the normal sizeof this group of lakes.

AQUIFERS

The three aquifers - the water-table aquifer, the secondary arte-sian aquifer, and the Floridan aquifer - store large quantities ofwater. The portion of rainfall that enters these aquifers through down-ward percolation is stored temporarily.

Water contained in the water-table aquifer discharges slowly bydownward percolation to the underlying aquifers and to the streamsand lakes through seepage and small springs. The water-table aqui-fer, in the basin, is composed of fine to coarse sand and contains avolume of water approximately one-fourth the volume of the saturatedsection. The fluctuation of water levels in the water-table aquifer isan indication of the change in storage, shown in figure 10. During dryperiods the water levels decline as the aquifer discharges the waterfrom storage. In wet periods water levels rise as more water is receivedby the aquifer than is discharged.

Exclusive of flow from the artesian aquifer, the low flows of thestreams are maintained by seepage from the water-table aquifer and

jU)--.in

0 lo \/ Well 023-532=124,a 12 - a t Bennett

<u 14 -Rainfall station 2 miles west of Bennett_j M.10z6< .2

MIJ J A lS O N ID JIF IMIA IM J IJ- A S |0 IN D1962 1963

Figure 410. Graphs of water level in the water-table aquifer and rainfall nearBennett for part of 1962 and 1963.


are indications of the size and ability of the water-table aquifer tostore and transmit water. Figure 11 is a graph of streamflow of Econ-fina Creek near Compass Lake for the period April 1 to May 7, 1963.

3•0

I8 I I 1 1 1i lili I I I I I I III I i i i i i II

0

°- I I

5 10 15 20 25 30 5

APRIL 1963 MAY

Figure 11. Graph of streamflow of Econfina Creek near Compass Lake for theperiod April 1 to May 7, 1963.

The low-flow portion of this graph represents seepage from the water-table aquifer. The nearly flat slope of the low-flow portion of thisgraph, such as that immediately preceding the rise of April 30, showsthat storage of water in the aquifer is sufficient to maintain the lowflow for long periods of no rainfall.

The secondary artesian aquifer which is present along the Gulfcoast also provides for storage of water in the basin. This aquifer issaturated at all times, therefore the volume of water stored in it doesnot change. Water discharges from this aquifer to the Gulf and towells. There is some exchange of water between this secondary arte-sian aquifer and the aquifers above and below.

The Floridan aquifer is the most extensive aquifer in the basin andthe one from which most water is obtained. A more detailed studywas made of the characteristics of this aquifer.

AQUIFER CHARACTERISTICSCertain hydraulic features of aquifers are of prime importance to

water-supply planners and developers. These hydraulic features, ob-


tained from well data, should be determined before the first well fieldis developed. A thorough knowledge of the hydraulics of an aquifer willenable the planners to predict how much water the aquifer will supply.In the design of a well field the planner should know how much waterhe can expect to pump from each well without overdrawing the aqui-fer; what the optimum spacing of wells should be to keep pumpinginterference between wells to a minimum; what the design of eachwell should be as to the diameter, depth of casing, length and settingfor screens or depths of open hole in a consolidated rock aquifer; andthe required pump specifications.

The water in an artesian aquifer is under pressure much the sameas water in a pipe leading from an elevated water tank, as shown infigure 12. The piezometric (pressure) surface in an artesian aquifer

ElevotedTak Level to which'water would rise in standpipes with no discharge10-------------------. ---------------------100

Level to which water would rise in_- a standpipe when water is

75 - discharging

CO

c .50

a JV l \ w

l

w ^^^SSQ^^' ^ ^£r\^ -L^~Pierometric Surface

cJ

Ioo.

5 0 --. , L

Figure '12. Sketch showing similarity of an artesian pressure system and waterpressure developed by an elevated tank.

-j

0-

pressure developed by an elevated tank.


is the level to which water will rise in cased wells drilled into theaquifer, and is likened to the level of water in a vertical pipe that tapsa city water main. Water can be taken from an artesian aquifer andthe piezometric surface lowered without dewatering the aquifer. Onlywhen the piezometric surface is lowered below the top of the aquiferis the aquifer dewatered. The quantity of water that can be withdrawnwithout dewatering the aquifer depends upon the ability of the aquiferto transmit water and the rate of recharge to the aquifer.

HYDRAULICS OF AQUIFERS

When a well that taps the Floridan aquifer begins to dischargewater, the piezometric surface surrounding the well is lowered. A cone,centered at the discharging well, describes the shape of the loweredpressure surface in the vicinity of the well. This lowered pressure sur-face near a well or a group of wells in a producing field is referred toas the cone of depression or cone of influence. This cone of depressionis graphically portrayed by the cones developed in the piezometricsurface of the Floridan aquifer in the vicinity of the well fields in thePanama City area, as shown in figure 13.

In the initial stages of development the cone of depression is smallin diameter and depth. As discharge from the well continues the conespreads out. The lowering or drawdown of the pressure surface at thewell continues until the amount of water being discharged is balancedby an equal amount being transmitted through the aquifer to the well.This balance can be achieved by a decrease in natural discharge or anincrease in natural recharge.

When pumping stops the pressure surface begins to recover, rap-idly at first, then at a progressively slower rate. With no further pump-ing in the vicinity the pressure surface will eventually recover to theinitial level.

The response of an aquifer to pumping from one well or a group ofneighboring wells in terms of the rate and extent of drawdown in thepressure surface, and the quantity of water that the aquifer will pro-duce is related to the hydraulics of the aquifer at that location. Theprincipal hydraulic properties of an aquifer are its ability to transmitand to store water.

An artesian aquifer, such as the Floridan aquifer in the EconfinaCreek basin, functions as a conduit through which water moves fromthe areas of recharge to the areas of discharge. The aquifer's abilityto transmit water is expressed in terms of its coefficient of transmissi-bility. It is the quantity of water, in gallons per day, that will flow


.Ad,' d As' A Ad 30 25' 20- i 8o' asd

H ,0 L -E' U w

I J A C K S 0d

.L ..

SWI N N I

j^ -c^ ^ ̂ ^ ̂ L --------------- r ^

A "" 2

.1

Figure 13. Map showing the piezometric surface of the Floridan aquifer in the

Econfina Creek basin area, October 192.

through a vertical section of the aquifer one foot wide and extendingthe full height of the aquifer, under a unit hydraulic gradient, at the

", O . AN L 0 ;

prevailing temperature of the water.

o o i/

The coefficient of storage of an aquifer is the volume of water re-leased from or taken into storage per unit surface area of the aquifer


per unit change in head normal to that surface. This storage coefficientfor an artesian aquifer is a measure of the small amount of water re-leased or taken into storage when the aquifer compresses or expandsdue to changes in water pressure.

AQUIFER TESTS

The coefficients of transmissibility and storage are determined bythe analysis of data obtained by aquifer tests or pumping tests. Threeaquifer tests were carried out during the field investigation of theEconfina Creek basin utilizing available wells in the Floridan aquifer.In each of the three tests conducted, a well was pumped at a constantrate while water levels were measured in the pumped well and in oneobservation well.

A test of short duration was run at Bid-a-wee (fig. 5) using astandby supply well and an observation well belonging to the city ofWest Panama City Beach. The pump was operated for a period of 6hours at a rate of 55 gpm (gallons per minute). The rate of drawdownand the rate of recovery of the water level were measured in the obser-vation well, 49 feet from the pumped well.

A similar test was made at Long Beach (fig. 5) in which one wellwas pumped for a period of 5 hours at a rate of 328 gpm. In this testthe observation well was 1,800 feet from the pumped well.

The third test was made at the Lansing Smith Steam Plant (fig. 5)northwest of Lynn Haven. In this test one well was pumped at a rateof 504 gpm for a period of 50 hours. The observation well was 1,195feet away.

The Theis graphical method (Theis, 1935) was used to computevalues of T (coefficient of transmissibility) and S (coefficient of stor-age) from the test data. The following values of T and S werecomputed:

Bid-a-wee test T= 2,000 gpd/ftS=1.2X 10- 4

Long Beach test T= 4,000 gpd/ftS=5 X10- 4

Lansing Smith Steam Plant test T=30,000 gpd/ftS=3X10- 4

These computations are based on the assumptions that the aquiferis (1) of uniform thickness; (2) of infinite areal extent; and (3) homo-geneous and isotropic (transmits water equally in all directions). De-terminations of T and S from data collected during these three testsgive a wide range of values and show considerable change in the hy-


draulic character of that part of the aquifer penetrated by the wellsat each of the test site locations. The wells used in the tests pene-trated the upper 330 feet of the aquifer at Bid-a-wee, 245 feet at LongBeach and about 250 feet at the Lansing Smith Steam Plant. None ofthe wells used in these tests penetrated the full thickness of the aqui-fer. Deeper wells would draw water from a greater thickness of theaquifer and would, consequently, give higher values.

The values of the coefficient of storage from these tests are con-sistent with values for the Floridan aquifer in other areas. The co-efficient of transmissibility of the aquifer at the Lansing Smith SteamPlant is higher than at the other test sites. This may indicate verticalleakage into the aquifer from the overlying formations. Because thetests show considerable differences in the coefficient of transmissi-bility of the aquifer within the bay area, the coefficient of transmissi-bility determined from pumping tests nearest a proposed well fieldshould be used. Additional tests should be made at distant locationsbefore a well field is designed.

In order to predict the amount and areal extent of drawdowns thatwill result from different rates of pumping and different well spacings,computations were made using the Theis formula (Theis, 1935) andthe coefficients of transmissibility and storage determined at theLansing Smith Steam Plant, at Bid-a-wee, and at Long Beach. Figure14 shows theoretical drawdowns in the vicinity of a well dischargingat a constant rate for different lengths of time at the Lansing SmithSteam Plant, the Long Beach, and the Bid-a-wee locations. Thesedrawdowns represent the conditions that would result from continuouspumping at this rate. Because drawdowns vary directly with dis-charge, drawdowns for greater or lesser rates of discharge can be com-puted from these curves. For example, the drawdown 100 feet froma well at the Lansing Smith Steam Plant discharging at 500 gpmwould be 24 feet after 100 days of pumping. If the well had dischargedat 100 gpm for the same length of time, the drawdown at the samedistance would have been only one-fifth as much, or about 5 feet.

The graph of drawdowns along a line of 10 wells, spaced 2,000 feetapart, at a rate of 200 gpm, are shown in figure 15. The values usedto determine this profile were obtained by summing the overlappingdrawdowns for each well in the line as read from the 100-day curve forthe Long Beach test (fig. 14). Similar graphs can be computed to de-termine the drawdown that would result from different pumping ratesor different well spacings (Lang, 1961, Theis, 1957).

The cone of depression in the vicinity of a well or a well fieldbeing pumped at a constant rate will eventually stabilize if a balance


DISTANCE, IN FEET, FROM DISCHARGING WELL

!0 100 1000 10o00 100,000

. . z 300 gp rnT = 2,000 gpd/ft

0 t. S 0.00012

3CC

4C I I I I I I III I I

BID-A-WEE TEST

Io 100 1000 10,000 100,000

%: \ v .Computations based on:Q=500gpm

T= 4,000 gpd/ft.

SI S= 0.0005

Ct I it I 1ILCNG BEACH TEST

0 )00 1000 10,p00 100 00

20 , - Computations based on:SWOO C3 0:500 gpm

ST =30,000 gpd/ftS= 0.0003

I40 ---- I-- ! I ! i I l t i lI I I l l ifitLANSING SMITH STEAM PLANT TEST

Figr-e 14. Graphs showing theoretical drawdowns in the vicinity of wells beingpumped at a constant rate for selected periods.


THOUSANDS OF FEET25 20 15 10 5 0 5 10 15 20 25

150- ---

I-

Computations based or

200 T= 4,OOgpd/ft.S= .0005

250 __

Figure 15. Theoretical drawdowns along a line of 10 wells after 100 days ofpumping at a rate of 200 gallons per minute at each well.

is established between the amount being pumped and the amountmoving to the well, either through a decrease in natural discharge oran increase in natural recharge. Water-level records (p. 33) in thewell field of the International Paper Company show that the cone ofdepression in that well field had stabilized by 1951 as a result ofcontrolled pumping.

WATER USE

Water planners should know how much of the available water isbeing used and the areas from which it is taken. Oftentimes, theamount of water available in an aquifer is ascertained by determininghow much is being withdrawn and by measuring the effects of thiswithdrawal on the water levels in the aquifer. For example, the lowwater levels in the Floridan aquifer prior to February 1964 were nearthe level where dewatering of the aquifer would begin near the cen-ters of heavy pumping.

The major uses of water within the Econfina Creek basin are rec-reation, manufacture of paper products, and public and domestic sup-plies. An undetermined though relatively small amount is used forirrigation. More than 80 named lakes, inland bays that cover over 100square miles, and the larger streams are used for recreation.

Information was collected on the various municipal and industrialuses of water within the basin, except recreation, in order to estimatethe total amount being withdrawn. Data on principal water-supplysystems are given in table 2.

T'I'AIj 2. Itwclirl of watcr Uilpply s f.yst'rs in tli IKc'onflna (rrtk lasin urea. o

Aquifer: F, Floridan; W, wator table. F, floculation; I, recarbonation;

Treatment: A, aeration; C, coagulation; CI, chlorination; S, softening; St, stabilization,

Capacity ofNumber Well-pump Ground Elevated stand by Yearly pumpaeg

Location of wells Aquifer capacity storage storage Treatment well pump (millonH of Remarks(gpm) (gallons) (gallons) (gpm) gallons)

Panama City:St. Andrew Plant 8 F 285 to 500 1,000,000 300,000 A, St, CI, 8 800 866.8 Ground storage - 2 tanks

500,000 each,Elevated storage for

Panama City system - 3tanks - 100,000 gal, ea.

Millville Plant 3 F 430 to 500 400,000 - A, St, Cl, S 600 660.24 W e175 - - A, St,CI, S - -

Lynn Haven 2 F 750 100,000 100,000 A, Cl - 95.5- - 700 30 - 2 tanks - 350 each

West Panama City Beach 2 F 500 1 reservoir 250,000 A, Cl 500. 84.9Long Beach 2 F 328 - 100,000 Cl 328 76.1

Tyndall Air Force Base 0 F 300 to 600 240,000 500,000 A, C, R, CI, F, S 1,500 1,017 2 tanks - 250,000 eachSt

- - -- 125,000 160,000 -

U. S. Navy Mine Def. Lab. 2 F 300 84,000 50,000 A, CI, St 630 78 2 tanks - 42,000 eachWoodlawn Subdivision 1 F e350 45,000 - A, Cl e350 31.6Hathaway Water System 4 F 60 to 100 20,000 - Cl - 12.7 4 tanks - 5,000 eachMexico Beach Water System 1 F 735 100,000 100,000 A, Cl 735 24.4Gulf Power Co. Water Plant 2 F rw)0 250,000 400,000 - - - Not in operationInternational Paper Co. 21 F n)5 to 776 - - 5,478.5 As of Jan. 31, 1964

10 W - - - - - ,478.5 began receiving waterfrom Deer Point Lake

e - Estimated


Prior to February 1964, no surface water was being withdrawn andground water was being used at the rate of 25.2 mgd. Of this amount,22.7 mgd came from the Floridan aquifer. In February 1964, whenthe International Paper Company began using surface water, ground-water use in the basin was reduced to about 11 mgd.

The International Paper Company, the major industry in thearea, is the largest user of water. Prior to February 1964, the waterused by this company was supplied by wells. About 13.5 of 15 mgdwas pumped from the Floridan aquifer and the remainder was pumpedfrom the watertable aquifer. Water used by this industry prior to 1964is shown by graph in figure 16. In February 1964, this company startedreceiving water from Deer Point Lake at the rate of about 30 mgd.

There are nine public water-supply systems in the area. All waterproduced by public water-supply systems is pumped from the ground.The rate of pumping varies from 6.7 mgd during low demand periodsof fall and winter to 12.9 mgd during peak demand periods of springand summer. Areas served by these systems and locations of the wellsare shown in figure 17.

Water use has increased with population (fig. 16). Also the percapita consumption in Panama City has increased from 70 gpd (gal-lons per day) to 80 gpd during the 10-year period, 1950-60. Thisfigure is based on the average daily pumpage of the Panama Citywater system and the population of the area supplied by this system.Only a small part of the water pumped by the city is supplied to indus-try and other non-domestic users. Also, there are a number of privateirrigation wells in the city. Partly for these reasons the per capita con-sumption is below the more normal rate of about 150 gpd per personthat is reported in other areas.

Nearly 18,000 persons live in areas not served by public watersystems. At a per capita consumption of 80 gpd this would amount toabout 1.4 mgd used for rural domestic purposes.

WATER HIGH LIGHTS OF THE BASIN

DECLINE OF WATER LEVELS IN THE PANAMA CITY AREA

GENERAL STATEMENT

From 1908 to 1964 water levels in the Floridan aquifer near Pan-ama City were lowered about 200 feet in the centers of major wellfields. This decline represents the difference between the reportedstatic water level of 16 feet above mean sea level in the first welldrilled in 1908 and the pumping water levels in the major well fields


a "O O " i I a " i I I i i ' I I I i i. I \6POO-I I I I I I I I I IS I a I I I I I I I I

I . I'I 1 I. II I

INTERNATIONAL 'PAPER COMPANY

5000 - SI• * , I a l \

I II III , r I I I I

11 I II" I i .: ' ; I

I t I I I I i I Ij j l I I | V

I i ' I I i

l 000 I ' , i I

J 4,i 5 i . 9 I .r I I_ r 6 r ', , n o aion i t ' , , '.

i I ,1 1 11- I I

TN IA AI R, I IFR

g- 000

igIBA O r in i P i I aa Cl I ,

a-

Figure 16. Graphs of water use and population in the Panama CitY area.

Figur 1.Gphofwtrl us an ppltoi heP aaCI tar.


7-TO < 5 * 4 0 ' 3S 1 t i sli l t s

5V --

- ' . ,

Figure 17. Map of the Panama City area showing the location of water wellsfor each water system and the area supplied by these systems.

in early 1964. In January 1964 one well field consisting of 21 wellswas shut down. The water levels in this well field recovered 163 feetwithin 51 days. Figure 18 shows the approximate piezometric surfacein 1908 under natural water conditions. The piezometric surface in1962 (fig. 13) shows the lowered water levels caused by pumpingsince 1908.

HISTORY OF GROUND-WATER DEVELOPMENT

The first deep well reported in the Econfina Creek basin was com-pleted in 1908 for an ice plant in downtown Panama City (Sellards,1912). In 1909 Panama City drilled a city supply well at the locationof the old National Guard Armory. In the same year another well wasdrilled near, the present water tank on Eleventh Street to supplySt. Andrew.


SS 55y • 45 40 35 d 25 20 85'

36-... 55' 50' 45" S 2S 2 0 •

Figure 18. Map showing the approximate piezometric surface of the Floridanaquifer in the Panama City area in 1908.

From 1908 to 1930 there was not enough water withdrawn bypumping to noticeably affect water levels in the Floridan aquifer.However, in 1930 the International Paper Company developed a wellfield in the Millville area, consisting of seven wells in the Floridanaquifer and three wells in the water-table aquifer. Three of these wellsin the Floridan aquifer flowed at the time of drilling and the staticlevels in the others were about 20 feet above mean sea level (from 8to 20 feet below land surface). The original test well for this supplyreportedly flowed at a rate of 60 gpm and, when pumped at a rate of700 gpm, the water level dropped to 55 feet below land surface. A coneof depression developed in the piezometric surface of the Floridanaquifer as water was withdrawn. Static water levels in wells drilledin 1935 were more than 50 feet lower than in the original wells drilledin 1930. By 1937 the water level near the center of the well field re-portedly was 104 feet below mean sea level, a decline of 124 feet fromthe time pumping began. This cone of depression expanded as thepaper company extended their well field eastward and northward.

A program was initiated by the paper company to protect theirwater supply. Four wells near the original center of pumping were


abandoned to decentralize pumping and to thus prevent excessivedrawdowns which were limiting production of water. The control ofwater levels was considered necessary also as a precaution againstsalt-water encroachment. Pumping from each of the other wells in thefield was regulated for the most efficient production from the aquiferwithin the cone of influence. Water-level records, shown in figure 19,of an abandoned well about one mile from the center of pumping showthe effectiveness of this program.

-JW 75

Water level affected by80- near-by pumping wells

J-85-

90-

S95

M 100 -

U I

w 105

5 1951 1952 1953 1954 1955 1956 1957 1958 1959 11960 1961 1962 1963

Figure 19. Graph of water levels in observation well 008-537-332 near the centerof the International Paper Company well field for the period 1951 to 1963.

In January 1964 the paper company was producing water from 21wells in the Floridan aquifer and 10 wells in the water-table aquifer.These wells were pumping an average of 15 mgd, of which about 13.5mgd were from the Floridan aquifer. At this time the water level inthe Floridan aquifer under pumping conditions was about 184 feetbelow mean sea level at the center of pumping and 100 feet belowmean sea level on the east edge of the field. These represent draw-downs of about 200 to 120 feet since pumping began in 1930. Althoughthis is a considerable drawdown, the pumping level in the field wasessentially stabilized at this level. Minor fluctuations (fig. 19) werecaused in part by seasonal variations in pumping from neighboringwell fields. The major recoveries shown on this graph indicate periodswhen pumping from wells near the observation well was stopped tem-porarily or when pumping from the entire field was stopped.


At the end of January 1964 when the paper company began usingwater from Deer Point Lake, all of the wells that had been pumpingfrom the Floridan aquifer were shut down. In four days water levelsin the aquifer recovered from about 200 to 83 feet below mean sealevel near the old center of pumping and from 105 to 58 feet belowmean sea level on the east edge of the field. After 51 days, water levelshad recovered to 21 feet below mean sea level near the center and toabout mean sea level on the east edge of the field.

In 1936 Panama City built a water plant in the Millville area.This plant was initially supplied by wells in the water-table aquifer,but later supplied by wells drilled into the Floridan aquifer. In 1955a well drilled into the Floridan aquifer had a water level of 63 feetbelow mean sea level. In October 1962, after all pumps were shut offfor a period of 6 hours, the water level in this well was 72 feet belowmean sea level, a net decline of 9 feet from 1955 when the well wasdrilled. The decline in water levels is attributed to pumping from thiswell field and from the nearby paper company well field.

Another public water-supply system for Panama City was con-structed in the St. Andrew section during late 1942 and 1943. Whenthe first of the original seven wells were drilled the water level in theFloridan aquifer stood at about mean sea level. By mid-1943, whenthe last of the seven wells was drilled, pumping from the first wellshad lowered the water level in the vicinity about 20 feet. In October1954, when an eighth well was added to the well field, the pumpinglevel had been lowered to 67 feet below mean sea level. This drawdownof 67 feet resulted from pumping at an average rate of 1.6 mgd.

Measurements of water-level in the St. Andrew well field in Octo-ber 1962, after a 6-hour recovery from pumping, showed the waterlevel to be 87 feet below mean sea level near the center of the field.The additional drawdown of 20 feet in the center of the field duringthe 9-year period from 1954 to 1962 represents the effect of pumpingat 2.0 mgd, an increase of 0.4 mgd in the average daily pumping rate.

A well field consisting of four gravel-packed, screened wells in thewater-table aquifer was constructed at Tyndall Air Force Base in1941 to supply water for the base, then under construction. It wasfound that this aquifer would not supply sufficient water so it becamenecessary to develop a supply from the Floridan aquifer. When thewells were drilled in the Floridan aquifer the water level stood about8 feet above mean sea level. By 1946 the water level had lowered toabout 10 feet below mean sea level. In 1961 pumping levels in theFloridan aquifer were as much as 82 feet below mean sea level near


the center of the well field. The cone of depression which had beendeveloping in this field was clearly established by 1961.

The maps of the Panama City area showing the piezometric sur-face of the Floridan aquifer, figures 13, 18, and 20, illustrate the effectof development of water from this aquifer. The piezometric surface in1908 (fig. 18) is indicative of the general conditions in the area up toabout 1930. By 1947 the 4 principal well fields were producing enoughwater to develop sizeable cones of depression in the piezometric sur-

86sW0 55' 56 45' 40' 35 3Y' 25' 2d 8515'

iur 0 oi io r

face (fig. 20). .A comparison 6f piezometric surfaces in figures 13 and20 clearly shows that increased pumping from expanded well fieldshas extended the cones of depression and has lowered water levelsgenerally throughout the Panama City area during the period from1947 to 1962.

THE DEADENING LAKES

The Deadening is a group of lakes in the lower end of a closed

1-ut A

- ,woe 0 1 2 3 4 5 10 " .;1.,

86W0' 55' 50' 45' 4d 35 R 25 2 8"

Figure 20. Map showing the piezometric surface of the Floridan aquifer in thePanama City area in April 1947.

face (fig. 20). A comparison 6f piezometric surfaces in figures 13 and20 clearly shows that increased pumping from expanded well fieldshas extended the cones of depression and has lowered water levelsgenerally throughout the Panama City area during the period from1947 to 1962.

THE DEADENING LAKES

The Deadening is a group of lakes in the lower end of a closedcreek basin-'in the southeastern corner of Washington County, asshown in figure 21. These lakes receive the surface drainage from the


6* c« 3W' s3 as 34 33W a32W 31 85 30'

* ~ ~ -I :-J ,.. :--!-- ---/^.-

WHITE OAK CREEK BASIN /

1___-_

\_ \I t -/' --

Seci tA*A ond --i

cre given is figure 2

showing The Deadening area.

table aquifer which underlies the surrounding sand hills. They lose/ 1\

'2 (

/ / 29 }

limestone formation. Gully Pond, Wages Pond, Hamlin Pond, StillPond, and Hammock Lake are joined at an elevation of 70 feet and

52323 39' \ 3' M 3-

their combined surfaces cover 3,640 acres. Porter Lake is connectedto the other lakes at high water through Swindle Swamp and BlackSlough. At an elevation of 70 feet, Porter Lake covers 930 acres. TheSlough, At an elevation of 70 feet, Porter Lake covers 930 acres. The·


area of these lakes and Swindle Swamp is about 5,000 acres at anelevation of 70 feet.

The variances in the supply of water and the constant drainthrough the ground cause wide fluctuations in stages of The Dead-ening lakes. In 1950, as a result of flood waters, the lakes reached anelevation of about 70 feet. Due to the dry weather for a period ofseveral years (fig. 4) some of the lakes were dry and others had re-ceded to elevations as low as 40 feet by 1956. Above average rains inthe late 1950's caused some of the lakes to recover to normal levels.Since 1960 lake levels have again receded.

The Deadening lakes have a considerable recreation potential.However, the wide ranges in lake levels prevent the potential frombeing realized.

The Washington County Development Authority has proposed aplan to divert water from Econfina Creek to these lakes at the ratenecessary to stabilize them at an elevation of 70 feet above mean sealevel. The diversion from Econfina Creek would be at a point justdownstream from Tenmile Creek, by way of a diversion canal toPorter Lake. After Porter Lake is filled, water would overflow throughSwindle Swamp and Black Slouth to The Deadening lakes.

GEOLOGIC AND HYDROLOGIC SETTING

The Deadening lakes are located in the sinks and lake physio-graphic division (fig. 2). They originated by the collapse of the over-lying sands and clays into cavities caused by solution of the limestoneof the Floridan aquifer. Where solution and collapse activity hasbreached the confining layer, figure 22, there is a loss of water fromthe lakes to the Floridan aquifer.

WATER LEVELS

Levels of the Deadening lakes have been as high as 70 feet and aslow as about 40 feet above mean sea level. A topographic map made in1950 shows an elevation of 70 feet for Porter Lake, and shows theDeadening lakes to be completely covered with water at an elevationof 69 feet. Based on flood marks, about 70 feet is the highest elevationthat the lakes have reached. The bottoms of Hammock Lake andPorter Lake are at an elevation of about 40 feet. Hammock Lake wasreported to have been dry in 1956.

Figure 23 shows that lake levels have varied from a high of 68.3feet in Porter Lake to a low of 44.2 feet in Gully Pond during theperiod from'1961 to 1963. Lake levels declined throughout most ofthat period. In mid-1963 the lakes began responding to rainfall as


A A

---- -- 3642 -

"11

S 1 2 3

1I0 0

Figure 22 Geohydrologic sections through the White Oak Creek basin,southeastern Washington County.

shown by the graphs in figure 23. The similarity of the graphs of lake

and ground-water levels indicates hydrologic continuity between thelakes and the aquifers.

Flow from White Oak Creek enters Swindle Swamp and separates,part going to Porter Lake and part going to Still Pond through BlackSlough (fig. 21). The flow from Still Pond is to Hamlin Pond by wayof subsurface channels. These subsurface channels are evidenced bysink holes through which movement of water can be seen. HamlinPond overflows to Hammock Lake. Wages Pond receives surfacedrainage from Howard Swamp and overflows to Gully Pond. Ham-mock Lake and Gully Pond are at a lower stage than the other lakesbecause they receive surface flow only when the other lakes overflow.

A comparison of the recessions of lake levels to the expected evap-orational losses indicates the lakes lose water to the underlying Flor-idan aquifer. The level of Clarks Hole, an arm of Hamlin Pond,receded seven feet from August to December 1962. Below a stage of55 feet, Clarks Hole is separated from Hamlin Pond and the shoreline is below the line of vegetation, which eliminates most transpir-ational losses. The major water losses from Clarks Hole below a stageof 55 feet are evaporation and downward leakage. During the 5-monthperiod that water levels in Clarks Hole declined seven feet, the evap-orational loss was about 2 feet, based on pan evaporation records


1961 1962 1963JIFIMIA MIJIJIAISI INDAIMIJ IJ IAISIOINIDIJIF IMIAIMIJIJ IAJS(O(NID

70 12 I

- 8 (2 miles north of Porter Lake)W 68 z'--> 6-w-JJ

66

< \ 0-W 6

Well 030-535-422bSPorter Lake \ateAtable aquifer) '--

S62

w---- 0w Io

60 -,

wJ Well 031-535-233

(HPmlin Pond) n eld 030-53'-47a52 Floridan aquifer)

0 58 Still Pondo

50

4 o \\Pond

Clarks Hole

z 52 (Hamlin Pond) \ Well 030-53w-4 4a

521961 196 1963loridon

SHammk Lake_I

£l Gullyl'- 46 Pond - -

44 j|F|MIA|MIJ J AISiO|NiD J|F|M|AiMIJIJIAsoiNSIDJ |D FIMIAIMI IJ IAI A oi"Do1961 1962 1963

Figure 23. Graphs of water levels and rainfall in the vicinity of the Deadeninglakes.


collected at Woodruff Dam by the U. S. Weather Bureau. The re-maining five feet represents leakage to the ground. Clarks Hole re-ceived no inflow during this period. Some of the other lakes did, whichminimizes the apparent losses shown by graphs in figure 23.

The Deadening area received about 11 inches of rain in July 1963,of which 8 inches fell during the last 10 days of the month. Theseheavy rains caused moderate rises in the lake levels and the piezo-metric surface of the Floridan aquifer. The ground-water level andlake levels, in general, showed about the same amount of rise, from2 to 5 feet. The water level in Clarks Hole rose about 12 feet as aresult of overflow from Hamlin Pond.

Water in the Floridan aquifer moves in the general direction of theslope of the piezometric surface (fig. 13). Water moves to the centerof The Deadening area from the northeast, and moves radially fromThe Deadening area toward Econfina Creek to the southeast, theGulf of Mexico to the south, and Pine Log Creek to the southwest.

Wells in The Deadening area showed larger gains during the riseof July 1963 than wells outside the area. This indicated that theFloridan aquifer gains water indirectly from rainfall more rapidly inThe Deadening area than in the surrounding area.

Water diverted to The Deadening lakes would move from thelakes to the Floridan aquifer at a rate proportional to the headbetween the lake surfaces and the piezometric surface of the aquifer.Raised lake levels could increase this head and cause more water toenter the aquifer. If the lake levels are maintained at a constant ele-vation, the head that will be established depends on the ability of theFloridan aquifer to transmit water away from the area.

FLOW OF ECONFINA CREEK

Information on the flow of Econfina Creek was obtained to de-termine the amount of water available at the proposed point of diver-sion and to determine what effect diversion would have on streamflow.

The proposed point of diversion is just east of the north end ofPorter Lake, about midway of the basin. The drainage area of Econ-fina Creek above the proposed point of diversion is about 67 squaremiles. The average flow at this point was estimated to be 90 mgd.

Minimum flow at the point of diversion is the important criterionin determining the available flow. The greatest amount of water willbe needed in the lakes when the creek flow is lowest. A minimum flowof 30 mgd was estimated on the basis of three discharge measure-ments and the relation of these measurements to the long-term flowrecord at the Bennett gaging station. This minimum flow probably will


not occur more often than once every 15 to 20 years, and then prob-ably will not persist for more than a few months. A flow of 36 mgdwas measured at the point of diversion on May 27, 1963, during aperiod of extreme low flow.

A dam to create a retention reservoir along Econfina Creek is beingconsidered. The main purpose of this reservoir would be to raise thewater level in the creek and make gravity flow to Porter Lake possible.There would be a usable storage in this reservoir between elevations80 and 95 feet of about 4,000 acre-feet. This amount of storage wouldprovide 10 mgd for a period of four months. This, added to the naturalflow of the creek, would assure a minimum flow of about 40 mgd. Aflow of 40 mgd would supply about 0.7 of a foot of water per monthon the 5,000-acre lake area.

If diversion from Econfina Creek is at a rate of 30 mgd, the stream-flow just downstream from the point of diversion would be almostdepleted during periods of low flow. This effect will diminish down-stream. Diversion of 30 mgd would reduce the flow below GainerSprings about 15 percent. The width of the stream at this point wouldnot be affected, and the depth would be reduced from a usual 4.5 feetto about 4 feet. Figure 24 shows, pictorially, the effect on stream-flow if 30 mgd were taken from the creek during low flow. A diversionof this amount is a negligible part of the total flow into Deer PointLake and would have no adverse effect on this water supply.

Some of the diverted water would be returned to Econfina Creekby an increase in the flow of artesian springs. The higher spring flowwould result from an increase in the piezometric slope caused byrecharge to the Floridan aquifer from the lakes.

SPRINGSThe artesian springs along Econfina Creek are located downstream

from a point just east of Porter Lake. Spring flow to the creek in-creases downstream to a maximum near the Washington-Bay Countyline. Below Gainer Springs it diminishes and there is little, if any,spring flow to the creek below the gaging station near Bennett, asshown on the flow chart in figure 25.

Spring water flows into Econfina Creek directly through thestream bed, from the base of rock bluffs, and from short spring runsabout a quarter of a mile in length. The spring water emanates fromthe Floridan aquifer where Econfina Creek has breached the over-lying, confining clay layer. Figure 22 illustrates the hydrologic rela-tionship of the aquifer with the creek. Figure 13 shows the patternof flow towards the springs.


0 2 4 W as

id JACKSON COUNTY

- ( FLOW CHARTS229 "mgd Tm to width of stream represe»ts flow with no diversion.

S 30 mgd diverted

Figure 24. Flow chart of Econfina Creek during the low-water period of May1963 showing the effect on streamflow if 30 amgd were diverted at the proposed

4 Flow-measuring poiWt

Figure 24- Flow chart of Econfina Creek during the low-water period of May1963 showing the effect on streamflow if 30 mgd were diverted at the proposeddam site.

It was possible to make direct measurements of the flow fromBlue Springs and Williford Springs. Flow from Gainer Springs wasdetermined by the difference in streamflow measurements above andbelow the group. Other spring flow, which could not be measured,enters the creek along its bed and banks.

The amount of flow attributable to spring flow was calculated atthe Bennett gaging station utilizing electrical conductivity measure-ments of the water. Pure water is a poor conductor of electricity butmineral matter dissolved in water consists of charged particles whichwill conduct an electrical current. The amount of current that a waterwill conduct is an indicator of the amount of dissolved minerals inthe water. The measurement of the electrical current conducted by


A

S ttFLOW CHARTM Spring flow

E Non-spring flow0 300mgd

Flow scale

1 0 1 2 3 4 5mi.

Figure 25. Flow chart of Econfina Creek showing spring flow.

water is expressed as specific conductance in units of micromhos.The specific conductance of the water from the springs along

Econfina Creek ranged from 95 to 150 micromhos. Water in the creekabove the area of spring flow ranged from 14 to 26 micromhos. Aver-age specific conductance values of 114 micromhos for spring waterand 20 micromhos for non-spring water were used in the calculationof spring flow.


Water at the Bennett gaging station was considered to be a thor-oughly mixed combination of spring water and non-spring water.Flow at the Bennett gaging station, attributable to springs, wascalculated from the formula:

Kb -Ks K -K Qb

s n

where: Q is spring flow

Qb is streamflow at BennettK is specific conductance of spring water

K is specific conductance of non-spring water

Kb is specific conductance of the mixture

Figure 26 shows the flow of Econfina Creek during non-flood periodsand that portion attributable to springs for 1963. Spring flow con-tributes about two-thirds of the total flow of Econfina Creek.

90C G800

70- 70T

600 TOTAL FLOW

600

00- -500

3 iS400 - 400

300 00 Z

SEF CALULATED SPRI FLOW5

Is

.oo - s ob0 0

*' YSPEanc COW~UCTAMC V

' V ~ s o ^

JA" FE"B MU AR A MX JUNE I I AU6 SEPT OCT MOV DEC

Figure 26. Graphs of streamflow, spring flow, and specific conductance forEconfina Creek near Bennett in 1963.


DEER POINT LAKE

Deer Point Lake (fig. 1) was formed on November 17, 1961, byconstruction of a salt-water barrier across North Bay at Deer Point.The lake was planned to serve as a source of fresh water and to pro-vide recreational facilities. It covers 4,700 acres, most of which wasformerly a part of North Bay, and stores approximately 32,000 acre-feet of water at a level of 4.5 feet above mean sea level, the elevationof the dam.

The lake is stabilized at an elevation of 5.0 feet above mean sealevel. The potential fresh water supply is approximately 650 mgd,the average flow through the lake to North Bay. In February 1964the only withdrawal from Deer Point Lake was the 30 mgd by theInternational Paper Company.

A study of the lake hydrology in the period immediately beforeand for several months after the dam was constructed (Toler, Mus-grove, and Foster, 1964) was made to determine the rate of freshen-ing and the effect the lake would have on the water-table aquifer.

Figure 27 shows the rate of freshening of the lake in terms of thenumber of times the inflow of fresh water would have filled the lake.Plotted in this manner, the graph enables a prediction of the rate offreshening of any similar lake if the volume and concentration of lakewater and inflowing water are known (Toler, Musgrove, and Foster,1964). When the barrier was completed on November 17, 1961, thelake was about half full and the chloride concentration was about7,400 ppm. Flow over the spillway began on November 29, 1961, andthe chloride concentration had been reduced to 3,700 ppm. In mid-February 1962 the chloride concentration was about 200 ppm.

When the barrier was completed, water levels in the lake and inthe water-table aquifer adjacent to the lake rose rapidly, as shownin figure 28. An immediate effect of the rise in the lake level was toreverse the water-table gradient near the lake so that water movedfrom the lake into the aquifer. This is evidenced by the rise in chloridecontent in water from well 015-535-232, 45 feet from the lake. Waterin wells 100 feet or more from the lake showed no change in chloridecontent. When the water table adjusted to the new lake level, thewater movement was again toward the lake and the high chloridewater was flushed from the aquifer.

SUMMARY

In general, the hydrologic system through which water moves inthe Econfina Creek basin is similar to most basins in northwest

I,


1961 1962 1963O( I

p C JAN FEB MAI APR J'

JU L AUG SP OCT NOV DEC JAN

4500 -

4000 -

3500

z2

S3000 Vi - volume of fresh woltr that has flowed into lake

I:slince spillway overflow begon

a" V volume of the lake at spillway elevotiona 2500I-

. 2000

1 ! 500

1000 .

500 - -

I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 16 17 18 19 20 21

V, /V0Figure 27. Graph showing the relation of chloride in water in Deer Point Lake

to fresh water inflow.

Florida. That is: (1) rainfall is the source of all the water even thoughsome falls outside the basin and moves into the basin underground;(2) the surface materials are highly porous, unconsolidated sands;(3) it is underlain by the artesian Floridan aquifer; and (4) waterleaves the basin by streamflow, evaporation, transpiration, under-ground flow to the ocean and other basins, and by consumptive use.

There are four physiographic divisions within the basin thataffect the surface drainage and the water storage, both above and


4.0 * Well 016-535-342b30 3

2.0 - 3000

SChloride

SWill 015-535-2321.0 ** 2000

0o - oo1000

NOV. DEC. JAN. FEr MAR APR. MAY JUNE JULY AUG SEP. OCT. NOV. DEC. JAN. FE. MAR. APR. MAY JUNE961 1962 1963

Figure 28. Graphs showing the rise of water levels and change in chloridecontent of ground water after construction of Deer Point Dam.

below the ground. These are the sand hills, sinks and lakes, the flat-woods forest, and the coastal sand dunes and wave-cut bluffs.

The surface materials on which the physiographic features havedeveloped are generally very porous, permeable sands which are from0 to 140 feet thick. These sands form the water-table aquifer. A con-fining layer, or aquiclude, of sandy clay and clayey shell materialseparates the water-table aquifer and the Floridan aquifer.

In the bay area and along the gulf coast there are two artesianaquifers. Here the formation that forms the aquiclude is thicker thanit is to the north and is overlain and in part underlain by some shell-hash beds which contain water under artesian pressure. Water pro-ducing zones in the shell-hash beds above the aquiclude are termedthe secondary artesian aquifer.

The Floridan aquifer underlies the entire basin below the aqui-clude. It is composed of limestone formations that include the lowerunits of the shell-hash beds and are as much as 1,200 feet thick.

The basin receives an average of 58 inches of rainfall per year.A partof the rainfall is absorbed by the porous surface sands and apart moves directly into the streams. Some water from the sandsmoves to the streams and maintains flow during periods of no rain-

El


fall. Water also moves from the sands downward to the Floridanaquifer but the amount diminishes toward the southwest because theaquiclude becomes thicker. Movement within the Floridan aquiferis generally southward with some water flowing into the channel ofEconfina Creek by way of artesian springs.

The transmissibility of the Floridan aquifer varies within thebasin, and is lower than the transmissibility of this aquifer in mostother areas in Florida. Coefficients of transmissibility range from2,000 to 30,000 gpd/ft.

The water in the lakes and streams differs little in mineral con-centration from rain water because of the relative insolubility of thesurface materials. Two areas of exception are where Econfina Creekreceives artesian spring flow and near the mouth of streams thatempty into salt-water bays.

The mineral content of water from the water-table aquifer gener-ally ranges from 10 to 50 ppm, and that of water from the secondaryartesian aquifer from 80 to 150 ppm. The mineral content of waterfrom the Floridan aquifer is higher than that from the other twoaquifers. Mineral concentrations in water from this aquifer showincreases in all constituents from the northern part of the basin tothe southwest.

Some salt-water intrusion was detected in the water-table andthe secondary artesian aquifers adjacent to the bays and Gulf. Theconfining clay layer overlying the Floridan aquifer in the coastaland bay area is sufficiently impermeable to prevent leakage of waterfrom the overlying aquifers. Water in the Floridan aquifer in thesouthern part of the basin is apparently a mixture of fresh water andresidual saline water.

Streamflow to the bays is at an average rate of about 960 mgdwhich for a year would amount to 40 percent of the average annualrainfall of 58 inches. About 650 mgd flows through Deer Point Lakeinto North Bay, and another 30 mgd flows into North Bay below DeerPoint Dam. East Bay receives a flow of about 210 mgd and West Bayabout 70 mgd. Most of the streams have sufficient flow to be a poten-tial water supply. During periods of minimum flows there is morethan 10 times as much fresh water flowing into the bays than is beingwithdrawn in the basin. Econfina Creek, by far the largest streamin the basin, has an average flow of 355 mgd.

Low runoff from the southern part of the basin results from poordrainage features of the flat-woods forest. Drainage in the sinks andlakes division is mostly internal. High base flow due to seepage fromthe porous sands causes high runoff in the sand hills division.


There are about 80 named lakes in the basin, most of which arein southeastern Washington County. Deer Point Lake, a fresh-waterreservoir covering 4,700 acres, is the largest. Porter Lake has a sur-face area of 930 acres and is the largest natural lake.

The major uses of water within the basin are for the manufactureof paper products, for public and domestic supplies, and for recrea-tion. Prior to February 1964 no surface water was being withdrawnand ground water was being used at the rate of 25.2 mgd. Of thisamount, 22.7 mgd came from the Floridan aquifer. The InternationalPaper Company was the largest user of water, using about 13.5 mgdfrom the Floridan aquifer and about 1.5 mgd from the water-tableaquifer. In February 1964 this company started receiving water fromDeer Point Lake at the rate of about 30 mgd. Ground-water use inthe Panama City area was reduced to about 11 mgd.

The first well in the Floridan aquifer was drilled in 1908. Later,as the demand for water increased, more wells and well fields weredeveloped and water levels were lowered. By the end of 1963, whenwater was being withdrawn at the rate of about 25.2 mgd, pumpinglevels had been lowered as much as 200 feet near the centers of majorwell fields. Pumping from the paper company well field, consistingof 21 wells, was discontinued in February 1964 and water levels inthis field recovered 163 feet within 51 days.

The Deadening lakes in southeastern Washington County offerconsiderable recreation potential. However, they lose water to theground at a high rate causing wide fluctuations in stage and thisprevents their full potential from being realized. The WashingtonCounty Development Authority has proposed a plan to divert waterfrom Econfina Creek to stabilize these lakes at an elevation of 70feet. The diversion from Econfina Creek would be at a point justdownstream from Tenmile Creek where the minimum flow was esti-mated to be 30 mgd. The proposed plan calls for a detention reservoiron Econfina Creek to raise the water level and make gravity flowthrough a diversion canal possible. The storage in this reservoir,added to the natural flow of the creek, would provide a minimumflow of 40 mgd which would supply about 0.7 of a foot of water permonth on the 5,000-acre lake area.

Water leaks from the lakes to the Floridan aquifer at a rate pro-portional to the head between the lake surfaces and the piezometricsurface of the aquifer. If the lake levels are maintained at a constantelevation, the head that will be established depends on the ability ofthe Floridan aquifer to transmit water away from the area.

If diversion from Econfina Creek is at a rate of 30 mgd, the stream


just downstream from the point of diversion would be almost depletedduring periods of low flow. This effect will diminish downstream andbecome almost negligible below Gainer Springs, a group of largeartesian springs just downstream from the Washington-Bay Countyline. A diversion of 30 mgd is a negligible part of the total flow of650 mgd into Deer Point Lake and would have no adverse effect onthis water supply. A part of the water diverted to the lakes would bemerely re-routed through the lakes into the ground and back to theEconfina Creek through the artesian springs below the dam.

Deer Point Lake is a fresh-water lake formed November 17, 1961,by a salt-water barrier across North Bay. It covers 4,700 acres andstores about 32,000 acre-feet of water. The lake elevation is 5.0 feetabove mean sea level and fluctuates very little.

Artesian spring water flows from the Floridan aquifer into Econ-fina Creek directly through the streambed, from the base of rockbluffs and from short runs about a quarter of a mile in length. Thesesprings occur from a point just east of Porter Lake downstream to apoint near the Bennett gaging station. Springs contribute about two-thirds of the flow of Econfina Creek.


REFERENCES

Foster, J. B. (also see Toler, L. G.)In Preparation Geology and ground-water hydrology of Bay County,

Florida.

Gunter, Herman (see Sellards, E. H.)

Hantush, M. S.1955 (and Jacob, C. E.) Non-steady radial flow in an infinite leaky

aquifer: Am. Geophys. Union Trans., V-37, No. 6, p. 702-714.

Lang, S. M.1961 Methods for determining the proper spacing of wells in artesian

aquifers: U.S. Geol. Survey Water-Supply Paper 1545-B.

Musgrove, R. H. (see Toler, L. G.)

Sellards, E. H.1912 (and Gunter, Herman) The underground water supply of west-

central and west Florida: Florida Gzol. Survey 4th Ann. Rept.,p. 116.

Shampine, W. J. (see Toler, L. G.)

Theis, C. B.1935 The relation of the lowering of the piezometric surface and the

rate and duration of discharge of a well using ground-waterstorage: Am. Geophys. Union Trans. p. 519-524, August.

1964 The spacing of pumped wells: U.S. Geol. Survey Water-SupplyPaper 1545-C, p. 113.

Toler, L. G.1964 • (and Musgrove, R. H., and Foster, J. B.) Freshening of Deer

Point Lake, Bay County, Florida: Am. Water Works Assoc.Journal, V. 56, No. 8, p. 984-990.

1965 (and Shampine, W. J.) Quality of water from the Floridan aquiferof the Econfina Creek basin area, Florida: Florida Geol. SurveyMap Series No. 10.

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